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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A large family (MRX48) with a nonspecific X-linked mental retardation condition is described. An X-linked semidominant inheritance is suggested by the segregation in three generations of a moderate to severe mental retardation in seven males and by a milder intellectual impairment in two females, without any specific clinical, radiological, or biological feature. Two-point linkage analysis demonstrated significant linkage between the disorder and several markers in Xq28 (maximum LOD score [Zmax] = 2.71 at recombination fraction [theta] = 0); multipoint linkage analyses confirmed the significant linkage with a Zmax of 3.3 at theta = 0, at DXS1684. A recombination event observed with the flanking marker DXS8011 delineates a locus between this marker and the telomere. The approximate length of this locus is 8-9 cM, corresponding to 5.5-6 Mb. In an attempt to explain the variable intellectual impairment in females, we examined X-chromosome inactivation in all females of the family. Inactivation patterns in lymphocytes were random or moderately skewed, and no correlation between the phenotypic status and a specific inactivation pattern was observed. The interval of assignment noted in this family overlaps with five MRX loci previously reported in Xq28.
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PMID:A gene for dominant nonspecific X-linked mental retardation is located in Xq28. 910 37

Temporal relations were analyzed between the VEP components in the occipital and central cortical areas in 7 and 10-year-old boys with normal intelligence, with mental retardation, and with debile oligophrenia in three experimental sessions with different instructions. It was found out that the intrahemispheric relations of the isopolar VEP components to a flash and patterned stimulus similar to those in adult persons developed in healthy children only to the age of 10 years. In children with intellectual deficiency such relations were distorted both in perception of the flash and patterned visual stimuli and during mental representation of the latter.
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PMID:[The temporal correlations of the VEP of the visual and motor cortices during the perception and mental reproduction of an image in normal children and in those with intellectual disorders]. 918 25

Functioning in activities of daily living of 40 psychiatric inpatients with mental retardation was compared with that of nonhospitalized control subjects matched for sex, age, and level of intellectual impairment. After excluding data for six quadriplegic control subjects from the analyses, the only difference between the groups was that the inpatients were less impaired in seeing. The findings indicate that even a major psychiatric disorder does not necessarily impair functioning in activities of daily living among individuals with mental retardation. Thus normal functioning adjusted for intellectual impairment does not necessarily indicate the absence of a major psychiatric disorder.
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PMID:Functioning in activities of daily living of psychiatric inpatients with mental retardation. 971 18

This preliminary study compared concerns of parents of children with moderate mental retardation and parents of children with severe mental retardation, on four health care variables, using a questionnaire format. Parents of children with severe impairments and those with school-aged children, had significantly more concerns regarding the hospitalization of those children, than did parents of children with moderate mental retardation or those with preschool children. Similarly, parents of children with severe disabilities had significantly more concerns on the parent-professional relationship variable than did individuals with moderately affected offspring. A high level of concern on the professional competence variable was expressed by all respondents. Study results suggested that severity of intellectual impairment is an important determinant of the number and nature of concerns that are experienced by parents when seeking health care services for their children with mental retardation. Suggestions for improving professional knowledge and service delivery are provided.
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PMID:Health care concerns among parents of children with mental retardation. 1012 30

A group of 199 children and adolescents (153 boys, 46 girls) with autistic disorder was audiologically evaluated. Mild to moderate hearing loss was diagnosed in 7.9% and unilateral hearing loss in 1.6% of those who could be tested appropriately. Pronounced to profound bilateral hearing loss or deafness was diagnosed in 3.5% of all cases, representing a prevalence considerably above that in the general population and comparable to the prevalence found in populations with mental retardation. Hearing deficits in autism occurred at similar rates at all levels of intellectual functioning, so it does not appear that the covariation with intellectual impairment per se can account for all of the variance of hearing deficit in autism. Hyperacusis was common, affecting 18.0% of the autism group and 0% in an age-matched nonautism comparison group. In addition, the rate of serous otitis media (23.5%) and related conductive hearing loss (18.3%) appeared to be increased in autistic disorder. The study emphasizes the need for auditory evaluation of individuals with autism in order to refer those with pronounced to profound hearing loss for aural habilitation and to follow those with mild to moderate hearing loss because of the risk of deterioration.
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PMID:Autism and hearing loss. 1058 81

Large deletions of the NF1 locus occur in 5 to 10% of patients with neurofibromatosis and are commonly associated with specific additional abnormalities characterized by mental retardation, dysmorphic features, and intellectual impairment. To characterize the extent of codeleted genes we constructed a long-range physical BAC/PAC map around the NF1 locus between D17S117 and D17S57 and determined the deletion boundaries in seven unrelated patients. Surprisingly, the proximal and distal breakpoints in five of seven patients fall at almost identical positions, resulting in the loss of at least 11 functional genes. Five of six patients investigated showed a de novo deletion on the maternally derived chromosome. Since D17S117 and D17S57 were previously reported as the outer limits for the great majority of NF1 deletions, we suggest that most NF1 patients with deletion of the entire NF1 gene are hemizygous for the same set of at least 10 additional genes, including SHGC-37343, SHGC-2390, SHGC-34232, OMG, EVI2B, EVI2A, WI-9521, WI-6742, SHGC-34334, and KIAA0160, and thus present with a relatively uniform clinical phenotype.
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PMID:A common set of at least 11 functional genes is lost in the majority of NF1 patients with gross deletions. 1084 9

Aim of this review is to present the latest advances in the identification of the genetic determinants of intellectual deficiency. Mental retardation (MR) is often associated with other neurologic symptoms, metabolic disorders, or malformation syndromes. The purpose of the review is to subdivide the large field of MR into categories that may help professionals in making a diagnosis. Nonspecific MR can also segregate in families and the mapping and cloning of corresponding mutant genes will eventually advance our understanding of normal and abnormal brain functioning. Several genes responsible for nonspecific X-linked mental retardation have been identified in the last 12 to 24 months and are being intensively investigated. This will hopefully lead to new possibilities of either genetic or pharmacological therapy.
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PMID:Genetics of mental retardation. 1110 70

Congenital myopathies and congenital myopathic dystrophies are distinct groups of inherited diseases of muscle, genetically heterogeneous, that manifest in early life or infancy. Congenital myopathic dystrophy is characterized by a dystrophic pattern, whereas no necrotic or degenerative changes are present in congenital myopathies. Much progress has been made in recent years in clarifying the classification of the congenital myopathies. This is a clinically and genetically heterogeneous group of conditions originally classified according to unique morphological changes seen in muscle. Not unlike the later-onset muscular dystrophies, the discovery of the genetic aetiology of many of the congenital myopathies has led to a revamping of how these conditions can now be diagnosed and this should enable physicians to give a more accurate prognosis to patients and their families. New mutations in the ryanodine receptor, slow tropomyosin, troponin T1, actin, and nebulin genes have been described in the last 2 years. Clinical and genetic guidelines for conditions like nemaline rod myopathy and central core disease have been suggested. The notion of minus and surplus protein myopathies has been developed. Several groups of congenital myopathic dystrophy have been identified. In the first category, without intellectual impairment or major structural brain abnormalities, half of the cases are merosin deficient due to mutations of the laminin alpha 2 chain gene. If generally the muscular phenotype is severe, mild allelic variants have been reported with early onset dystrophies and partial merosin deficiency. Among other pure congenital myopathic dystrophies unlinked to the laminin alpha 2 gene, one form has been assigned to chromosome 1q42. In the group of congenital myopathic dystrophies associated with mental retardation and structural brain abnormalities, two main entities are genetically characterized: (1) Fukuyama congenital myopathic dystrophy, affecting the Japanese population, is due to fukutin gene mutations, and (2) the muscle eye brain syndrome assigned to chromosome 1p32-34. In several cases, the gene localization remains unknown.
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PMID:Congenital myopathies and congenital muscular dystrophies. 1156 68

A nonspecific X-linked mental retardation (MRX) family is reported with four mild to moderately affected males and no intellectual impairment in their obligate carrier mothers. Linkage analysis obtained the same multipoint lod score of 2.08 for two intervals on the X chromosome already reported to be linked to other MRX and syndromic X-linked mental retardation (XLMR) families: one pericentromeric and the other at Xq26. Since the responsible gene is not yet characterized, haplotyping is presently the only means available for carrier and prenatal testing for this form of MRX. Carrier risk estimation using pedigree and haplotype data for five females at risk is presented, and the difficulties of prenatal diagnosis given linkage to two different regions is discussed.
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PMID:MRX42: two linkage intervals, one in the pericentromeric region and one in Xq26, and the impact for carrier risk estimation. 1180 62

Women at childbearing age often use alcohol and various illicit drugs such as cocaine and heroin. These agents pass through the human placenta and may affect the developing embryo and fetus. Indeed, large amounts of alcohol ingested by the pregnant woman may produce a specific syndrome manifested by prenatal and postnatal growth retardation, a variety of facial dysmorphic features and mental retardation. Ingestion of smaller amounts of alcohol will produce the fetal alcohol effects with only few and minor dysmorphic features but with developmental delay and some degree of intellectual impairment. Cocaine use during pregnancy may apparently result in an increase in the rate of congenital anomalies, of stillbirth and of intrauterine growth retardation. The use of heroin and opiates does not seem to increase the rate of major congenital anomalies, but it reduces fetal growth and increases the rate of intrauterine fetal death. Studies on the developmental outcome of children born to cocaine or heroin dependent mothers seem all to show psychomotor developmental delay at a young age. At school age these children have intellectual impairment and a very high rate of inattention and/or hyperactivity. We should therefore address our efforts in improving the environment of these children and in treating the early symptoms of inattention and hyperactivity, even before the child reaches school.
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PMID:The effects of alcohol and illicit drugs on the human embryo and fetus. 1222 27


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